GFE - Components - Heat Exchangers and Condensers (291006)

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B733 Which one of the following changes will result in increased subcooling of the condensate water in the main condenser hotwell? A. Decreased circulating water flow B. Increased circulating water temperature C. Decreased main turbine-generator MW load D. Isolating one bay of the condenser circulating water system

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.18 [2.8/2.9] QID: B1236 During power plant operation, the accumulation of air and non-condensible gases in the main condenser will... A. not affect turbine work output. B. not affect turbine efficiency. C. increase generator load. D. increase turbine backpressure.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.18 [2.8/2.9] QID: B4817 (P4816) Refer to the drawing of an operating lube oil heat exchanger (see figure below). The heat exchanger is operating with the following initial parameters: Cooling water inlet temperature (Tcw-in) = 75°F Cooling water outlet temperature (Tcw-out) = 95°F Oil inlet temperature (Toil-in) = 150°F Oil outlet temperature (Toil-out) = 110°F Air leakage into the heat exchanger causes some of the heat exchanger tubes to become uncovered. As a result, Tcw-out decreases to 89°F. Assume the inlet temperatures, mass flow rates, and specific heats of both fluids do not change. Which one of the following will be the resulting temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 116°F B. 122°F C. 130°F D. 138°F

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.01 [2.7/2.7] QID: B104 Which one of the following describes the proper sequence for placing a steam (shell) and water (tube) heat exchanger into service? A. The water side is valved in before the steam side to minimize thermal shock. B. The water side is valved in before the steam side to ensure adequate venting. C. The steam side is valved in before the water side to minimize scale buildup on the heat exchanger tubes. D. The steam side is valved in before the water side to ensure that the cooldown rate does not exceed 100°F/hr.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.02 [2.6/2.6] QID: B36 Why is proper venting of a shell and tube heat exchanger important? A. An air bubble reduces the heat transfer coefficient of the heat exchanger. B. An air bubble causes pressure transients within the tubes as heat load changes. C. An air bubble will cause thermal shock as it moves through the heat exchanger. D. An air bubble will cause corrosion in the heat exchanger.

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.02 [2.6/2.6] QID: B531 A liquid to liquid heat exchanger containing trapped air on the shell side will be less efficient because the air... A. causes more turbulent fluid flow. B. increases the differential temperature across the tubes. C. reduces the fluid contact with the heat transfer surface. D. causes pressure oscillations.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1033 Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F "m" ̇oil = 1.8 x 104 lbm/hr "m" ̇water = 1.65 x 104 lbm/hr Toil in = 115°F Toil out = 90°F Twater out = 110°F Twater in = ? Which one of the following is the approximate cooling water inlet temperature (Twater in) for the heat exchanger? A. 50°F B. 60°F C. 75°F D. 80°F

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1331 (P3432) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: "m" ̇_"oil" = 1.8 x 104 lbm/hr "m" ̇_"water" = 3.3 x 104 lbm/hr cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F Tcw-in = 90°F Tcw-out = 120°F Toil-in = 170°F Toil-out = ? Which one of the following is the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 110°F B. 120°F C. 130°F D. 140°F

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1432 (P1432) The rate of heat transfer between two liquids in a heat exchanger will increase if the... (Assume single-phase conditions and a constant specific heat for both liquids.) A. inlet temperature of the hotter liquid decreases by 20°F. B. inlet temperature of the colder liquid increases by 20°F. C. flow rates of both liquids decrease by 10 percent. D. flow rates of both liquids increase by 10 percent.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1631 (P1634) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: "m" ̇oil = 2.0 x 104 lbm/hr "m" ̇water = 3.0 x 104 lbm/hr cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F Tcw-in = 92°F Tcw-out = 125°F Toil-in = 180°F Toil-out = ? Which one of the following is the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 126°F B. 135°F C. 147°F D. 150°F

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1732 (P1732) Which one of the following will reduce the heat transfer rate between two liquids in a heat exchanger? (Assume single-phase conditions and a constant specific heat for both liquids.) A. The inlet temperatures of both liquids decrease by 20°F. B. The inlet temperatures of both liquids increase by 20°F. C. The inlet temperature of the hotter liquid increases by 20°F. D. The inlet temperature of the colder liquid increases by 20°F.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B1933 (P1934) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: "m" ̇oil = 1.5 x 104 lbm/hr "m" ̇water = 2.5 x 104 lbm/hr cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F Tcw-in = 92°F Tcw-out = 125°F Toil-in = 160°F Toil-out = ? Which one of the following is the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 110°F B. 127°F C. 135°F D. 147°F

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B2531 (P2632) The rate of heat transfer between two liquids in a heat exchanger will decrease if the: (Assume single-phase conditions and a constant specific heat for both liquids.) A. inlet temperature of the hotter liquid increases by 20°F. B. inlet temperature of the colder liquid decreases by 20°F. C. flow rates of both liquids decrease by 10 percent. D. flow rates of both liquids increase by 10 percent.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B2534 (P2532) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: "m" ̇oil = 1.5 x 104 lbm/hr "m" ̇water = 2.5 x 104 lbm/hr cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F Toil-in = 160°F Toil-out = 110°F Tcw-in = 92°F Tcw-out = ? Which one of the following is the approximate temperature of the cooling water exiting the heat exchanger (Tcw-out)? A. 110°F B. 115°F C. 120°F D. 125°F

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B2832 (P4517) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following initial parameters: Cooling water inlet temperature (Tcw-in) = 75°F Cooling water outlet temperature (Tcw-out) = 105°F Oil inlet temperature (Toil-in) = 140°F Oil outlet temperature (Toil-out) = 100°F Air introduction to the heat exchanger results in some of the heat exchanger tubes becoming uncovered. As a result, Tcw-out decreases to 99°F. Assume that the mass flow rate and specific heat of both fluids remain the same, and that Toil-in does not change. Which one of the following will be the approximate temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 99°F B. 108°F C. 116°F D. 122°F

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B3631 (P3632) Refer to the drawing of an operating water cleanup system (see figure below). If cooling water flow rate is 1.0 x 106 lbm/hr, what is the approximate water flow rate in the cleanup system? A. 2.2 x 105 lbm/hr B. 3.2 x 105 lbm/hr C. 2.2 x 106 lbm/hr D. 3.2 x 106 lbm/hr

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B5716 (P5716) Refer to the drawing of an operating parallel-flow lube oil heat exchanger (see figure below). Assume that lube oil (LO) inlet temperature is greater than cooling water (CW) inlet temperature. Unlike a counter-flow heat exchanger, in a parallel-flow heat exchanger the __________ temperature can never be greater than the __________ temperature. A. LO outlet; CW inlet B. LO outlet; CW outlet C. CW outlet; LO inlet D. CW outlet; LO outlet

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B5917 (P5916) Refer to the drawing of an operating process water cleanup system (see figure below). Assume there is no heat loss from the process water cleanup system to the surroundings and the process water flow rate does not change. If valve D closes fully, what will be the final steady-state temperature of the process water flowing through the filter? A. 212°F B. 302°F C. 450°F D. 540°F

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B631 (P1832) The rate of heat transfer between two liquids in a heat exchanger will increase if the: (Assume single-phase conditions and a constant specific heat for each liquid.) A. flow rate of the colder liquid decreases by 10 percent. B. flow rate of the hotter liquid increases by 10 percent. C. inlet temperatures of both liquids decrease by 20°F. D. inlet temperatures of both liquids increase by 20°F.

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B7017 (P7016) Given the following parameter values for a feedwater heater: Feedwater inlet temperature = 320°F Feedwater inlet pressure = 1,000 psia Feedwater mass flow rate = 1.0 x 106 lbm/hr Extraction steam pressure = 500 psia Assume that the extraction steam enters the heater as a dry saturated vapor and leaves the heater as a saturated liquid at 500 psia. Which one of the following is the approximate mass flow rate of extraction steam required to increase feedwater temperature to 380°F? A. 5.2 x 104 lbm/hr B. 7.9 x 104 lbm/hr C. 8.4 x 104 lbm/hr D. 8.9 x 104 lbm/hr

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B7316 (P7316) Refer to the drawing of an operating parallel-flow lube oil heat exchanger (see figure below). Unlike a counter-flow heat exchanger, in the parallel-flow heat exchanger the __________ temperature will always be greater than the __________ temperature. A. CW outlet; LO inlet B. CW outlet; LO outlet C. LO outlet; CW inlet D. LO outlet; CW outlet

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B7676 (P7676) Which one of the following will increase the heat transfer rate between two liquids in a heat exchanger? (Assume single-phase conditions and a constant specific heat for both liquids.) A. The mass flow rate of the hotter liquid decreases by 10 percent. B. The mass flow rate of the colder liquid decreases by 10 percent. C. The inlet temperature of the hotter liquid increases by 20°F. D. The inlet temperature of the colder liquid increases by 20°F.

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B832 (P1632) The rate of heat transfer between two liquids in a single-phase heat exchanger will decrease if the... (Assume constant specific heat capacities.) A. inlet temperatures of both liquids decrease by 20°F. B. inlet temperatures of both liquids increase by 20°F. C. flow rate of the colder liquid decreases by 10 percent. D. flow rate of the hotter liquid increases by 10 percent.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B834 Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F ṁoil = 1.8 x 104 lbm/hr ṁwater = 1.65 x 104 lbm/hr Toil in = 170°F Toil out = 120°F Twater out = 110°F Twater in = ? Which one of the following is the cooling water inlet temperature (Twater in) for the heat exchanger? A. 45°F B. 50°F C. 55°F D. 60°F

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.07 [2.7/2.8] QID: B31 Decreasing the temperature of the lube oil leaving a lube oil heat exchanger is normally accomplished by... A. increasing the cooling water flow rate. B. increasing the lube oil flow rate. C. decreasing the cooling water flow rate. D. decreasing the lube oil flow rate.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.09 [2.7/2.8] QID: B232 A reactor is shut down with a reactor coolant temperature of 400°F and all control rods fully inserted. What is the major adverse consequence resulting from rapidly reducing the reactor coolant temperature to 250°F? A. Excessive stress in the ceramic fuel pellets. B. Excessive stress in the reactor vessel wall. C. Uncontrolled reactor criticality. D. Loss of core inlet subcooling.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.09 [2.7/2.8] QID: B633 (P2832) Steam has been admitted to a main condenser for 25 minutes with no cooling water flow. Initiating full cooling water flow rate at this time will... A. reduce the stress on the condenser shell by rapidly cooling the shell. B. reduce the stress on the condenser tubes by rapidly cooling the tubes. C. induce large thermal stresses on the condenser shell. D. induce large thermal stresses on the junctions between the condenser tubes and the tubesheet.

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B111 (P1834) During normal nuclear power plant operation, a main condenser develops an air leak which decreases vacuum at a rate of 1.0 inch Hg/min. Which one of the following will increase because of this condition? (Assume that main turbine steam inlet valve position does not change.) A. Steam cycle efficiency. B. Main turbine work output. C. Condenser hotwell temperature. D. Low pressure turbine exhaust steam moisture content.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B1232 Assuming that condenser cooling water inlet temperature and flow rate do not change, if condenser vacuum improves, condensate temperature will... A. increase, because condensate subcooling has decreased. B. increase, because condenser saturation pressure has increased. C. decrease, because condensate subcooling has increased. D. decrease, because condenser saturation pressure has decreased.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B2133 During normal plant operation at 100 percent power, a main condenser develops an air leak that degrades vacuum at a rate of 1 inch Hg/min. Assuming the plant continues to operate at 100 percent power, condenser hotwell temperature will... A. increase, because condensation of turbine exhaust steam is occurring at a higher temperature. B. increase, because more work is being extracted from the steam by the turbine. C. decrease, because condensation of turbine exhaust steam is occurring at a lower temperature. D. decrease, because less work is being extracted from the steam by the turbine.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B2633 (P2634) A nuclear power plant is operating at steady-state 100 percent power. Assuming that condenser cooling water inlet temperature and flow rate do not change, if main condenser vacuum decreases, condensate temperature will... A. increase, because condensate subcooling has decreased. B. increase, because condenser saturation pressure has increased. C. decrease, because condensate subcooling has increased. D. decrease, because condenser saturation pressure has decreased.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B2736 (P3534) A nuclear power plant is operating at steady-state 100 percent power when air inleakage causes main condenser vacuum to decrease from 28 inches Hg vacuum to 27 inches Hg vacuum. Assume the main steam inlet pressure, inlet quality, and mass flow rate through the main turbine do not change, and the condenser cooling water inlet temperature and mass flow rate do not change. When the plant stabilizes, turbine exhaust quality will be __________; and turbine exhaust temperature will be __________. A. higher; higher B. higher; lower C. lower; higher D. lower; lower

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.10 [2.8/2.8] QID: B32 A nuclear power plant is operating at full power with 2°F of condensate subcooling. Which one of the following changes will decrease subcooling of the condensate entering the main condenser hotwell? (Assume condensate temperature does not change.) A. Decreased circulating water flow rate B. Increased gas buildup in the main condenser C. Decreased main condenser hotwell level D. Decreased main turbine steam flow

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.15 [2.6/2.8] QID: B3635 (P3633) A main turbine-generator is operating at 80 percent load with the following initial steady-state temperatures for the main turbine lube oil heat exchanger: Toil in = 174°F Toil out = 114°F Twater in = 85°F Twater out = 115°F After six months of main turbine-generator operation, the following final steady-state lube oil heat exchanger temperatures are observed: Toil in = 179°F Toil out = 119°F Twater in = 85°F Twater out = 115°F Assume the final cooling water and lube oil flow rates are the same as the initial flow rates, and the specific heat values for the cooling water and lube oil do not change. Which one of the following could be responsible for the differences between the initial and final heat exchanger steady-state temperatures? A. The heat exchanger tubes have become fouled with scale. B. The temperature of the cooling water source has increased. C. The final main turbine-generator load is higher than the initial load. D. The final main turbine-generator load is lower than the initial load.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.15 [2.6/2.8] QID: B4616 (P4617) Refer to the drawing of two system curves for a main condenser cooling water system (see figure below). Which one of the following will cause the system curve to shift from the solid curve toward the dashed curve? A. The main condenser tubes are cleaned. B. The main condenser tubes become increasingly fouled. C. Cooling water flow rate is increased by 25 percent by starting an additional cooling water pump. D. Cooling water flow rate is decreased by 25 percent by stopping one of the operating cooling water pumps.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.15 [2.6/2.8] QID: B5117 (P5116) Refer to the drawing of two system curves for a typical main condenser cooling water system (see figure below). Which one of the following will cause the system curve to shift from the solid curve toward the dashed curve? A. The main condenser tubes are cleaned. B. The main condenser tubes become increasingly fouled. C. Cooling water system flow rate is increased by 25 percent by starting an additional cooling water pump. D. Cooling water system flow rate is decreased by 25 percent by stopping one of the operating cooling water pumps.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.15 [2.6/2.8] QID: B7625 (P7625) Refer to the drawing of an operating lube oil heat exchanger (see figure below). The heat exchanger was initially placed in continuous service 6 months ago. During the 6-month period of operation, mineral deposits have accumulated inside the heat exchanger tubes. The following parameters are currently stable at their initial values: Lube oil mass flow rate Lube oil inlet temperature Lube oil outlet temperature Cooling water inlet temperature Compared to their initial values, the current cooling water outlet temperature is __________; and the current cooling water mass flow rate is __________. A. lower; greater B. lower; smaller C. higher; greater D. higher; smaller

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.15 [2.6/2.8] QID: B7736 (P7736) Refer to the drawing of an operating lube oil heat exchanger (see figure below). The heat exchanger was initially placed in continuous service 6 months ago. During the 6-month period of operation, mineral deposits have accumulated inside the heat exchanger tubes. The following parameters are currently stable at their initial values: Cooling water mass flow rate Cooling water inlet temperature Cooling water outlet temperature Lube oil mass flow rate Compared to their initial values, the current lube oil inlet temperature is __________; and the current lube oil outlet temperature is __________. A. lower; lower B. lower; higher C. higher; lower D. higher; higher

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.16 [2.5/2.6] QID: B1136 Tube scaling in a parallel flow heat exchanger causes heat transfer rate to decrease because the... A. surface area of the tubes decreases. B. cooling fluid outlet temperature decreases. C. thermal conductivity of the scale is very low. D. flow through the heat exchanger becomes more turbulent.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.16 [2.5/2.6] QID: B1234 (P32) Refer to the drawing of an operating lube oil heat exchanger (see figure below). If scaling occurs inside the cooling water tubes, cooling water outlet temperature will __________; and lube oil outlet temperature will __________. (Assume the lube oil and cooling water flow rates do not change.) A. decrease; decrease B. decrease; increase C. increase; decrease D. increase; increase

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.16 [2.5/2.6] QID: B156 The buildup of scale on heat transfer surfaces in the reactor vessel... A. results in lower fuel temperature, which decreases the nuclear fuel cycle efficiency. B. is controlled by complying with core thermal limits and adhering to fuel preconditioning requirements. C. is controlled by using reactor water cleanup system and condensate system demineralizers. D. results in higher coolant temperature, which increases overall plant efficiency.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.16 [2.5/2.6] QID: B1833 (P2233) Refer to the drawing of an operating lube oil heat exchanger (see figure below). If deposits accumulate on the outside of the cooling water tubes, cooling water outlet temperature will __________; and lube oil outlet temperature will __________. (Assume the lube oil and cooling water inlet temperatures and mass flow rates do not change.) A. decrease; increase B. decrease; decrease C. increase; increase D. increase; decrease

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.16 [2.5/2.6] QID: B6617 (P6616) Refer to the drawing of an operating lube oil heat exchanger (see figure below). If mineral deposits accumulate on the inside of the cooling water tubes, cooling water outlet temperature will __________; and lube oil outlet temperature will __________. (Assume the lube oil and cooling water inlet temperatures and flow rates do not change.) A. increase; decrease B. increase; increase C. decrease; decrease D. decrease; increase

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B1535 (P1234) Refer to the drawing of an operating cooling water system (see figure below). Which one of the following will occur as a result of the indicated tube failure in the heat exchanger? A. High pressure (HP) fluid inventory increases. B. Pressure in the low pressure (LP) system decreases. C. Temperature in the low pressure (LP) system increases. D. Level in the surge tank decreases.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B1931 (P1134) With a nuclear power plant operating at 50 percent power, which one of the following will occur as a result of multiple tube leaks in the main condenser? (Assume that main condenser vacuum does not change.) A. Condensate depression will decrease. B. Condensate conductivity will increase. C. Condensate oxygen concentration will decrease. D. Condenser inlet cooling water flow rate will decrease.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B234 Refer to the drawing of an operating cooling water system (see figure below) that is transferring heat between a low pressure (LP) and high pressure (HP) water system. Which one of the following effects will initially occur as a result of a tube failure in the heat exchanger? A. Level in the surge tank will increase. B. HP fluid pump flow rate will decrease. C. HP fluid heat exchanger differential temperature will increase. D. LP fluid heat exchanger outlet temperature will increase.

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B332 (P331) A nuclear power plant is operating at steady-state conditions with the main generator supplying 1,000 MW to the power grid. Assume main generator load remains constant. If one percent of the tubes in the main condenser become plugged, condenser absolute pressure will __________; and condenser hotwell temperature will __________. A. increase; increase B. decrease; increase C. increase; decrease D. decrease; decrease

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B333 (P333) A nuclear power plant is operating normally at 50 percent power. Which one of the following will result from a cooling water tube rupture in the main condenser? A. Increased condenser vacuum. B. Increased conductivity of the condensate. C. Decreased condensate pump available net positive suction head. D. Decreased condensate pump flow rate.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B3535 (P234) Refer to the drawing of an operating cooling water system (see figure below). Which one of the following effects will occur because of the failed tube in the heat exchanger? A. Level in the surge tank will increase. B. Flow in the low pressure (LP) system will reverse. C. Pressure in the low pressure (LP) system will decrease. D. Low pressure (LP) fluid heat exchanger outlet temperature will decrease.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.17 [2.7/2.8] QID: B4918 (P4917) A nuclear power plant was initially operating at steady-state 50 percent power with 50 gpm of main condenser cooling water inleakage through a cooling water tube rupture. Power was then increased, and is currently stable at 60 percent. Assume the size of the cooling water tube rupture does not change, and the main condenser cooling water inlet pressure and inlet temperature do not change. When compared to the flow rate of main condenser cooling water inleakage at 50 percent power, the flow rate of cooling water inleakage at 60 percent power is __________ because the main condenser pressure at 60 percent power is __________. A. higher; lower B. higher; higher C. lower; lower D. lower; higher

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.18 [2.8/2.9] QID: B5418 (P5417) Refer to the drawing of an operating lube oil heat exchanger (see figure below). The heat exchanger was operating with the following initial parameters: Cooling water inlet temperature (Tcw-in) = 71°F Cooling water outlet temperature (Tcw-out) = 91°F Oil inlet temperature (Toil-in) = 175°F Oil outlet temperature (Toil-out) = 125°F The heat exchanger was vented, resulting in the following current parameters: Cooling water inlet temperature (Tcw-in) = 71°F Cooling water outlet temperature (Tcw-out) = 95°F Oil inlet temperature (Toil-in) = 175°F Oil outlet temperature (Toil-out) = ? Assume that the mass flow rates and specific heats of both fluids were unchanged. Which one of the following is the current lube oil outlet temperature (Toil-out)? A. 115°F B. 120°F C. 130°F D. 135°F

ANSWER: C.

TOPIC: 291006 KNOWLEDGE: K1.18 [2.8/2.9] QID: B936 (P1912) During normal nuclear power plant operation, why does air entry into the main condenser reduce the thermodynamic efficiency of the steam cycle? A. The rate of steam flow through the main turbine increases. B. The condensate subcooling in the main condenser decreases. C. The enthalpy of the low pressure turbine exhaust increases. D. The air mixes with the steam and enters the condensate.

ANSWER: D.

TOPIC: 291006 KNOWLEDGE: K1.02 [2.6/2.6] QID: B932 Reduced heat transfer performance in a water-to-water heat exchanger will result from... A. tube wall thinning. B. turbulent flow in the tubes. C. increased ΔT between fluids. D. gas collection in the shell.

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B3431 Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F Toil in = 174°F Toil-out = 114°F Twater-in = 85°F Twater-out = 121°F "m" ̇oil = 4.0 x 104 lbm/hr "m" ̇water = ? What is the approximate mass flow rate of the cooling water? A. 8.0 x 104 lbm/hr B. 7.3 x 104 lbm/hr C. 2.6 x 104 lbm/hr D. 2.2 x 104 lbm/hr

ANSWER: B.

TOPIC: 291006 KNOWLEDGE: K1.03 [2.4/2.6] QID: B934 (P3132) Refer to the drawing of an operating lube oil heat exchanger (see figure below). Given the following information: "Q" ̇oil = 1.0 x 107 Btu/hr Toil in = 170°F Toil out = 134°F Twater in = 85°F Twater out = 112°F cp-oil = 1.1 Btu/lbm-°F cp-water = 1.0 Btu/lbm-°F ṁwater = ? Which one of the following is the approximate mass flow rate of the cooling water? A. 4.5 x 105 lbm/hr B. 3.7 x 105 lbm/hr C. 2.5 x 105 lbm/hr D. 1.2 x 105 lbm/hr

ANSWER: A.

TOPIC: 291006 KNOWLEDGE: K1.18 [2.9/3.0] QID: B4018 (P4016) Refer to the drawing of an operating lube oil heat exchanger (see figure below). The heat exchanger is operating with the following initial parameters: Cooling water inlet temperature (Tcw-in) = 75°F Cooling water outlet temperature (Tcw-out) = 95°F Oil inlet temperature (Toil-in) = 150°F Oil outlet temperature (Toil-out) = 120°F Air introduction to the heat exchanger results in some of the heat exchanger tubes becoming uncovered. As a result, Tcw-out decreases to 91°F. Assume the inlet temperatures, mass flow rates, and specific heats of both fluids do not change. Which one of the following will be the resulting temperature of the lube oil exiting the heat exchanger (Toil-out)? A. 126°F B. 130°F C. 134°F D. 138°F